MCJIT MemoryManager access

[semoro]

llvm.stackmap requires to provide custom memory MCJIT memory manager to allow interception of .llvm_stackmaps section Currently, it is not possible due to 3 problems

1. There are no bindings for the default memory manager for delegation to

2. Default memory manager implementation aka SectionMemoryManager has no C-exports

3. There is no access to

   fn LLVMCreateMCJITCompilerForModule(
       OutJIT: *mut LLVMExecutionEngineRef,
       M: LLVMModuleRef,
       Options: *mut LLVMMCJITCompilerOptions,
       SizeOfOptions: ::libc::size_t,
       OutError: *mut *mut ::libc::c_char,
   ) -> LLVMBool
   

   Which allows providing more options than just opt level when creating an execution engine One of those options is MCJMM which is a wrapper for user-created custom memory-manager

[Chronostasys]

I also need this feature, I'm using a global variable linking to the stackmap section in static compile mode, which however causing segmentation fault in jited code.